An efficient and accurate grain/basic element size differentiation modeling technique applied to Brazilian splitting tests

: In this paper, both a novel discrete element modeling method based on the geometric and mechanical characteristics of real granite and a novel grain/basic element size differentiation modeling (GBSDM) technique specifically tailored for Grain-Based Models within the Particle Flow Code framework are proposed. The analyses involving macroscopic fracture patterns, mesoscopic crack development, stress distribution, and force-chain characteristics demonstrate that the central region is the critical zone during Brazilian splitting loading. This region experiences high force-chain intensities leading to specimen rupture. In contrast, stress variations are relatively low in the peripheral regions, and crack initiation is minimal. Altering the mineral-grain and basic-element sizes within the central region significantly impacts the load–displacement curve, mesoscopic fracture behavior, stress distribution, and force-chain characteristics. In contrast, changes in the peripheral regions have a much smaller effect. Finally, this paper determines the appropriate amplification ratios for mineral-grain and basic-element sizes specifically suited for the Brazilian splitting test. Sample 0 contains 3,286 mineral grains, 188,425 basic elements, and 817,520 contacts. The size-differentiated model reduces the number of mineral grains, basic elements, and contacts by nearly 50.0% compared to Sample 0. The errors in peak load and corresponding displacement are 8.3% and 4.2%, respectively. Crucially, the computational time for a single loading process dropped from 15.5 hours (Sample 0) to 3.8 hours (size-differentiated model), achieving a 75.5% reduction.